LevelDB is a fast key-value storage library written at Google that
provides an ordered mapping from string keys to string values.

Features:
  - Keys and values are arbitrary byte arrays.
  - Data is stored sorted by key.
  - Callers can provide a custom comparison function to override
    the sort order.
  - The basic operations are Put(key,value), Get(key), Delete(key).
  - Multiple changes can be made in one atomic batch.
  - Users can create a transient snapshot to get a consistent view
    of data.
  - Forward and backward iteration is supported over the data.
